MnO2-ZnO Hexagonal Nanomaterials Characterization and High Performance Humidity Sensing Application

Abstract

--MnO2 doped nanostructured zinc oxide was synthesized by solid state reaction route. The prepared material was characterized by X-ray diffraction, scanning electron microscope and UV-Vis absorption spectroscopy. The doping of MnO2 in ZnÒ enhanced the crystallization and decreased the crystallite size. Surface morphology of the sensing material showed that the hexagonal shaped particles were uniformly distributed in zinc oxide that left large number of pores. These pores acted as humidity adsorption sites. With increase in the concentration of MnO2, the pores also increased. The optical band gap of pure ZnO was 4.05 eV. The value of band gap decreased with increase in the MnO2 doping concentration. The average sensitivity of undoped zinc oxide was 3400 KΩ/%RH. The sensitivity of the sensing element increased with increase in the doping concentration. Sensitivity of MnO2 doped ZnO composite is more than four times the sensitivity of pure zinc oxide at annealing temperature 600 o C. Keywords---Humidity Sensor; Zinc oxide; X-ray diffraction; Scanning electron microscopy; UV-Vis Spectroscopy.